Say the wrong thing? go back! About to get hit by a car? go back (assuming you've got the reflexes )! Ate something so delicious you want to eat it again (apparently this is the story for the plants vs. zombies 2 game)? go back!

But if I could only pick active abilities, I think either heal or remove disease. I could make so much money with that and as an added bonus, I could cure myself or anyone close to from all diseases in a heartbeat.

In all seriousness, what about the passive spell all players seem to inherently have that allows them to run back after they die? Doesn't even have a cooldown or anything (unless you somehow die once every 2 minutes and start getting rez timers)

If that isn't a viable option, then I'd just go ahead and say Mind Vision. Just stand back, act as if you're casually reading or something, and stalk people from miles away.

As a mage with no alts anywhere near maxlvl because I cant locate my Teleport/Portal spells in my alts spellbook and ragequits shortly after, Im gonna have to go with Teleport/Portal IRL aswell. Need a vacation? Poff done.

But if I could only pick active abilities, I think either heal or remove disease. I could make so much money with that and as an added bonus, I could cure myself or anyone close to from all diseases in a heartbeat.

Until some secret service picks you up and decides to cut you open to see how you work

Surprised no one has said it yet; Tame Beast.
Some sort of heal/cleanse spell would probably honestly be my first choice, but a wild beast that is your ally without question everything would be much more enjoyable. With my penguin friend I'd just cure everything the old fashioned way.